wrote:
On Oct 4, 6:27 am, Mxsmanic wrote:
TheSmokingGnu writes:
Then why do wings generate lift at negative AOA?
They don't. That's a very common misconception, even among pilots.

The effective AOA is always positive when the wing is generating lift.

Once again, thou knowest not of what thou speakest. I
just told you, in apost not long ago, that some airfoils will generate
lift at up to -4° AOA. Here's a graph that shows lift being generated
on some anonymous airfoil at -5°:
http://en.wikipedia.org/wiki/Lift_coefficient
Bernoulli at work. Newton, too, because there's downwash being
generated.

Dan


Don't bother. Believe me it's not worth it. You can talk this guy to
death and all he will do is count you as another response.

Angle of attack as we all know (with one exception it seems :-) can be
both positive or negative.
In fact, in high performance jets with a fuselage loaded IYMP, entering
a coupled spin after a departure, it's extremely disorienting if the
aircraft goes through PSG and stabilizes in an inverted spin mode where
yaw is opposite to roll. g is a bad indicator as with a fuselage loaded
IYMP you can get negative g either erect or inverted.
The way we deal with this is through instrument interpretation rather
than trying to eyeball what's happening, which can be next to impossible.
The AOA indicator in the aircraft has a positive and negative side. If
the AOA is stabilized at some value on the negative side, and the
airspeed is stabilized at some mean low value, the spin is inverted. The
turn needle will show spin direction either way.

Again, don't waste your time.

--
Dudley Henriques